1. Field of the Invention
The present invention relates to a tool to be used in dentistry and the use of this tool in new methods for the emplacement of dental prostheses. More particularly, the present invention relates to a rotary cutting tool which is useful for the contouring of a tooth to a uniform, circumferential depth, and, optionally, the undercutting of the tooth surface.
2. State of the Art
It is conventional practice in dentistry to apply a veneer prosthesis to a tooth which has been damaged either as a result of trauma or disease, i.e. caries. Generally, the surface enamel of the tooth is partially removed by grinding to form a relatively even surface, and a dental prosthesis secured to the tooth. Such a prosthesis can be formed extra-orally from a mold taken of the tooth and the surrounding portion of the mouth, which is then adhesively secured to the previously ground down surface; or by applying a moldable composite substance to the contoured tooth substrate, which can be formed in situ on the tooth substrate, and then set and hardened in situ.
Such a veneer is generally not subject to the extreme structural stress to which the facing transverse surfaces of teeth are subject, but rather, is applied to a well-supported vertical, buccal or labial existing surface. The veneer is intended primarily for cosmetic purposes, but also to protect the remaining tooth from further damage caused by chemical or bacterial action. Great care must be taken to insure that the veneer is securely applied to the tooth substrate so as to not only be cosmetically satisfactory, but also insure against displacement during any chewing function.
In teeth which have received more extensive damage, major portions of the tooth's surface may be replaced by a full crown. Normally the tooth is prepared by cutting away the outer surface and contouring the tooth to a desired shape which will support and help retain the crown. A mold is then made of the prepared tooth in order to shape externally, or extra-orally, the portion of the crown which will be in contact with the adjacent teeth. The resulting crown is thereafter mounted and cemented on the prepared tooth. In situ shaping, and curing to hardness, is also possible for full crowns Various tools have been developed to shape the tooth, such as seen in U.S. Pat. No. 2,250,058 issued Apr. 8, 1940, to Brooks, or U.S. Pat. No. 4,473,354 issued Sept. 25, 1984, to Rigaud, or in British Patent Specification No. 732,124, published on June 22, 1955.